In recent years, due to influences of the aging society and changes in life styles based on westernization of food practice, there are increasing number of diseases attributable to stenosis or blockage of the blood vessel such as ischemic heart disease (angina pectoris, myocardial infarction), cerebrovascular disease, or arteriosclerosis obliterans. As an examination for checking stenosis or blockage of the blood vessel, there is catheter contrast radiography. In the catheter contrast radiography, a contrast medium as an x-ray non-transmission substance is used to diagnose a lesion of the blood vessel by continuously capturing images of a state of the blood vessel or a blood flow state. Specifically, the catheter operator thrusts a needle into the femoral artery (vein) near the hip joint or the arterial (vein) of the arm, and inserts a tube having a diameter of a few millimeters called catheter into the blood vessel. A method of capturing an image of a target blood vessel by inserting a catheter tip-end to the target blood vessel and injecting a contrast medium into a specific blood vessel is carried out in general. Therefore, in the catheter contrast radiography, in order to insert the catheter into the target blood vessel, at a blood branch point, it is necessary to match the direction (rotation angle) of the catheter tip-end with a branch direction of the target blood vessel.
However, because the catheter operator manipulates the catheter by watching a two-dimensional fluoroscopic image, the catheter operator cannot determine information of a depth. Therefore, there is a problem in that the catheter operator cannot understand an accurate direction of the catheter tip-end, cannot enter the catheter into the target blood vessel, and takes time in contrast radiography. In the x-ray fluoroscopy, it is unavoidable to shorten the time taken for contrast radiography, to reduce the amount of radiation to a patient. To shorten the time taken for contrast radiography by a smooth catheter manipulation and surgery, it is important to detect an accurate direction of the catheter tip-end.
As a conventional method of detecting the direction of the catheter tip-end, there is a method of using a rotation sensor that is set on a catheter operator's hand side (for example, refer to Patent Literature 1). FIG. 33 shows a conventional catheter manipulation detection device described in Patent Literature 1. In FIG. 33, a catheter rotation angle detecting unit 1106 detects an angle of the catheter that is rotated by the operator. A catheter tip-end rotation angle deciding unit acquires a rotation angle of the catheter rotation angle detecting unit 1106, and outputs the rotation angle directly to a display unit 1107 as a catheter tip-end rotation angle.
On the other hand, as a method of detecting a tip-end rotation angle of a surgical tool from an image, there is a method in which a marker of continuous pattern is provided in an endoscope, and the direction of the endoscope is detected from an image-captured image of the endoscope and a marker image (for example, refer to Patent Literature 2). Further, there is a method in which, by providing a heteromorphic convex portion that does not transmit an electromagnetic wave in the catheter, the heteromorphic convex portion is confirmed by an X-ray device or the like (for example, refer to Patent Literature 3).